Aging causes a decrease in the functional capacity of the cardiovascular system and an increase in various risk factors which predispose to coronary artery disease (CAD). The functional capacity of the cardiovascular system and CAD risk factors are known to be influenced by a person's level of physical activity. Since physical activity decreases with age, the rate of deterioration of the cardiovascular system and the increase in CAD risk factors which occur with age may be partially due to a decreased physical activity level rather than aging per se. I will compare cardiovascular parameters measured non-invasively during maximal exercise (oxygen consumption, cardiac output, stroke volume, heart rate, and 02 extraction) and pulmonary function, serum lipids, body composition, glucose tolerance and echocardiographic left ventricular function in young (less than 25 years) and older (greater than 50 years) endurance athletes who are matched on the basis of their training, and on their performances at age 20 if the older athlete competed when younger. In other studies, individuals over 60 yrs of age who have been sedentary will be evaluated before and after periods of exercise training. The goals of these studies are: to obtain information regarding a) the physiological changes due to aging per se, as opposed to a decline in physical activity, that are responsible for the decline in maximum 02 uptake capacity with age; b) whether exercise can slow the deterioration in functioned capacity with agi; c) whether exercise can reverse the deterioration in glucose tolerance, lower plasma insulin levels, and induce favorable alterations in plasma lipid levels in older individuals. The cross sectional studies on highly trained athletes will evaluate the maximal effects attainable with exercise training in older individuals, while the longitudinal studies will determine the magnitude of the adaptations that can be induced by means of an exercise program in elderly, non athletes. It is my hypothesis that exercise training can slow the deterioration in functional capacity with age and decrease the risk of developing CAD. The proposed studies are a first step toward my long term goal of systematically evaluating exercise as a therapeutic modality in gerontology and preventive medicine.